Chart text formatting

[jdu98a]

Is it possible to add textual formatting to the data labels along chart axis other than through the chart formatting dialogue box? As seen in the image I have a chart that is showing two sets of data from different date ranges. The data itself is shown with different colors within the area chart. I would like the "Date" labels along the X Axis to reflect those same colors. As is, I am limited to using some form of separator between the two date values, but this becomes hard to read when looking at more than a few dates at a time.

The values for each data point on the X Axis are gathered into a single variable and then passed to the chart. I have tried using textual formatting functions within the variable, but they don't work. Any ideas?